Yes, often BSE for valence optics is even more demanding than BSE for XANES, because you have more "valence" (occupied) orbitals.
The basis of BSE is formed by the GGA-orbitals, and the size of the Hamiltonian is Number_of_valence_bands * Number_of_conduction_bands * Number_of_k-points Eg, with 30 valence and 30 conduction bands and 100 k-points this gives a matrix of 90000x90000, and many screened Coulomb-matrix elements, ..... Typically, we use 512 cores for such calculations .... and still it runs for many days ... Am 20.04.2011 07:19, schrieb Osama Yassin: > Dear Prof Blaha, > > When using BSE for optical properties; is it also demanding and requires > large clusters?. How can you adapt a BSE code into Wien2k.. i.e linking the > an obtained "scf ground > state calculations" to "BSE calculations"?. > > Best regards.. > > O A Yassin > > 2010/12/1 Peter Blaha <pblaha at theochem.tuwien.ac.at <mailto:pblaha at > theochem.tuwien.ac.at>> > > Dear WIEN2k users, > > BSE calculations, both for valence excitonic effects or for ELNES/XANES > are quite demanding > calculations. They require a large cluster with a fast mpi-interconnect > (Infiniband). > > Furthermore, at present the code is not documented and not easy to use, > because it requires > the understanding of several details, both from the physics point of view > as well as from the > computational knowledge. > > For all those reasons, we do not intend to release the BSE code to > everybody in the near future. > > However, if you have a good and physical sound problem, we may be > interested in a collaboration > and you can contact us directly (either pblaha at theochem.tuwien.ac.at > <mailto:pblaha at theochem.tuwien.ac.at> or rolask at theochem.tuwien.ac.at > <mailto:rolask at theochem.tuwien.ac.at>) > for further details. > > Best regards > Peter Blaha > Am 29.11.2010 10:33, schrieb ZhenChen: > > Dear Prof. Peter Blaha and all users, > > I have read the papers about using BSE to simulate ELNES augmented in > Wien2k (Phys. Rev. B 79, 041102R (2009), J. Phys.: Condens. Matter 21, 104205 > (2009). ). And I > am eager to > > know if it will be released in the next Wien2k version, or do you have > any plan or time schedule to release the BSE modular? > > Thank you in advance! > > Best regards! > > Zhen Chen > > ?? > > ------------------------------ > > Beijing Laboratory of Electron Microscopy > > Institute of Physics > > Chinese Academy of Sciences > > P. O. Box 603 > > Beijing 100190, China > > Tel: 86-10-82648001 > >???????? zchen at blem.ac.cn <mailto:zchen at blem.ac.cn> > > > > > > > > _______________________________________________ > > Wien mailing list > > Wien at zeus.theochem.tuwien.ac.at <mailto:Wien at > zeus.theochem.tuwien.ac.at> > > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien > > -- > > P.Blaha > -------------------------------------------------------------------------- > Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna > Phone: +43-1-58801-15671 FAX: +43-1-58801-15698 > Email: blaha at theochem.tuwien.ac.at <mailto:blaha at > theochem.tuwien.ac.at> WWW: http://info.tuwien.ac.at/theochem/ > -------------------------------------------------------------------------- > > _______________________________________________ > Wien mailing list > Wien at zeus.theochem.tuwien.ac.at <mailto:Wien at > zeus.theochem.tuwien.ac.at> > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien > > > > > -- > Prof Dr Osama Ali Yassin > Professor of Solid State Physics and ICTP regular associate > Department of Physics, Faculty of Science > Taibah University > Almadeenah Almonawarh > K. of Saudi Arabia > > > > _______________________________________________ > Wien mailing list > Wien at zeus.theochem.tuwien.ac.at > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien -- ----------------------------------------- Peter Blaha Inst. Materials Chemistry, TU Vienna Getreidemarkt 9, A-1060 Vienna, Austria Tel: +43-1-5880115671 Fax: +43-1-5880115698 email: pblaha at theochem.tuwien.ac.at -----------------------------------------
